Method and system for cooling internal-combustion engines



Jan. 26 Ufifi v N. S. DIAMANT METHOD AND SYSTEM FOR coomue INTERNAL comsus'uou ENGINES Filed Sept. 17 1924 mm "0 5 Tm R m m MM 7 W0; A a m a w. N

W 6 (UN 0 P A wnw 1 5 Q 6 Patented Jan, 26, 1926.

NICHOLAS S. DIAMANT, OF JAIYIRFSTOXVN, "NEW YORK.

METHOD AND $YSTEM FOR COULING INTERNAL-CGMBUfiTION ENGINES.

Application filed September '17, 1924.

1' aZZ whom it may concern:

Be it known that I, NioHoLAs S. DIAMANT, a citizen of the United States, residing at Jamestown, in the county of Chautauqua and State of New York, have invented a new and useful Improvement in Methods and Systems for Cooling internal-Combustion Engines, of which the tollowing is a specification.

This invention relates to improvements in methods and systems for cooling internal combustion engines of the kind in which a cooling liquid is employed which is circulated through jackets formed around the engine cylinders and their' walves, and which liquid is cooled by passing the same through a radiator or other liquid cooling device.

In cooling systems of the kind heretofore used a single circuit has generally been provided tor the cooling liquid, which is such that all ot the warm liquid discharged from the top of the jacket of the engine cylinder is passed to a cooling device or radiator and then returned to the engine jacket. In a system of this kind the temperature of the cooling liquid entering the jacket varies in accordance with the temperature of the sur rounding air so that in cold weather the temperature oi the water entering the engine jackets is much too low for the efficient operation of the engine. Further, the temperature of the cooling liquid in the ackets varies with the load on the engine and with the speed of the car since the amount of air flowing through the radiator depends on the latter. It is clear therefore, that the temperature of the cooling liquid is subject to very wide slow fluctuations which seriously impair both the performance and economy oi? the engine. In the cooling systems heretofore used the temperature of the water in the engine jackets also cools rapidly after stop 'iing the engine, so that even after a short stop. some warming of the water is necessary before the engine again operates satisfactorily.

Many devices have been proposed in order to eliminate or to reduce the great fluctuations of the temperature of the cooling medium, to maintain the operating temperature at rn eflicient value and to reduce the time required to attain such temperature when starting with cold engine. Among such devices we may mention first, shutters which control the amount of air flowing through the radiator, and second thermostatic valves,

Serial No. 738,299.

which check the flow 01" the cooling liquid through the radiator, and when this liquid reaches a predetermined temperature they open and restore full circulation through the radiator. All such devices, however, have proved expensive and impractical, as can be seen from the fact that they have been adopted to a very limited extent only. Fun ther, thermostatic valves are trail in their construction, since they consist of a thin metallic drum filled with some expansive fluid; also there is the danger of the valve remaining in the cold or closed position when a small leak develops and the drum fails to expand. Further, these thermostats can be used on engines having forced pump circulation but they have proved impractical for engines operating on the thermosiphon principle of circulation.

One of the objects of this invention is to provide a cooling system for internal combustion engines which will maintain an cflicient high operating temperature irre spective of weather, load or speed; a system which will be simple, inexpensive and applicable to thermosiphon or pump systems and practically tree from the disadvantages just enumerated.

Other objects are to provide a cooling system in which the liquid'passing through the engine jackets circulates more rapidly than the liquid passing through the radiator; also to provide a cooling system in which the circuit through the radiator or other liquid cooling device does not begin until the liquid in the engine jacket circuit has attained a fairly high temperature; also to provide a circlulating cooling system for internal combustion engines which can readily be applied to any liquid cooled type of internal combustion engine without materially changing the engine, radiator or other cooling device, and which acts to keep the engine running at approximately the same temperature regardless of the temperature of the outside air; also to provide a system of this kind with means for thoroughly mixing the cool water from the radiator circuit with the water coming from the engine acket circuitbefore returning this mixture to the jackets; also to provide a method of cooling internal combustion engines which includes two circuits, one for the current circulating around the jackets and one for the cooling liquid which passes through the radiator and nto which small portions of the liquld are wlthdrawn from the ackets, cooled and then returned to said current; also to improve cooling systems and methods in other respects hereinafter specified.

In the accompanying drawings Fig. 1 is a side elevation of an internal combustion engine and a radiator or cooling device, showing in section the connections or circuits for the cooling liquid embodying my invention.

Fig. 2 is a similar view showing connections of slightly modified form.

Fig. 3 is a similar view showing the radiator partly in section, and showing hand-op erated means for controlling the flow of liquid through the radiator circuit.

Fig. 4 is a similar fragmentary view show ing hand operated means for controlling the flow of liquid through the radiator circuit.

Fig. 5 is a similar View showing another modified form of circu ts or flow passages for the cooling liquid.

In carrying out my process I provide a current of cooling liquid which circulates rapidly past the cylinders of an internal combustion engine, the current flowing in a circuit, including the engine jackets and a low resistance passage for returning the cooling liquid from the discharge opening of the engine jackets to the inlet opening thereof, this circuit having a low heat radiating capacity, and being subject to negli gible temperature fluctuations. A portion of the liquid is passed from the engine jacket circuit through a cooling circuit, which may include a radiator or other suitable heat dissipating device, this radiator or cooling circuit offering greater resistance to the flow of liquid than the jacket circuit, so that the circulation of liquid in this circuit will usually be much less rapid than that in the jacket circuit. The cooled liquid from the radiator circuit is returned to the jacket circuit and thoroughly mixed with the warmer liquid in the jacket circuit before the mixed liquids are permitted to flow through the engine jackets.

The importance of the foregoing will be clear when it is considered that the exhaust valve seats and ports are always subjected to more intense heat than the inlet valve seats and ports, and much more intense heat than the lower parts of the cylinder barrel. Thus, the ten'iperatures of the various parts of the engine jackets vary considerably and set up stresses and strains, and affect greatly the performance of the engine and its useful life. In fact, in some high duty engines, particularly those intended for airplanes, it has been found advisable to cool the jackets about and near the exhaust valves by means of one radiator, and other parts of the engine by means of another. This construction eliminates troubles due to warping or burning out, but is complicated and prohibitively expensive for most industrial applications of internal combustion engines, and it is fortunate that in case of passenger cars and even trucks and tractors the adoption of such a system is not imperative at present, still the fact remains that the undesirable feature of unequal temperature distribution exists. Further, this feature is exaggerated by returning the cold water from the radiator to the bottom of the jacket. In my process I maintain a high rate of water flow through the jackets and I thus equalize the temperature differences in the engine jackets and at the same time reduce the necessary tempe z ture drop across the jackets in order to carry the heat rejected to the ackets. For example, if the heat rejected to the jackets is 600 B. t. u. per minute, it will require a drop of 20 degrees F. across the jackets to carry this amount of heat away if the rate of flow is lbs. of water per minute, but it will require a drop of temperature of 6 degrees F. if the rate of water flow is increased to 100 lbs. per minute. Further, I secure the high rate of flow through the jacket circuit by eliminating from this circuit the radiator and its connections, and thus greatly reducing the frictional and head resistances of the circuit. Another very important advantage of my process is due to the fact that though. a high rate of flow is desirable and necessary for the proper cooling of the jackets, it is not necessary for the efficient performance of the radiator. The cooling capacity of a radiator does increase with the rate of flow but there is a definite and fairly low rate above which the cooling capacity does not increase appreciably, while the frictional losses increase rapidly, being nearly proportional to the square of the rate of flow. In short, by placing the jackets in one circuit and the radiator in another, I have made it possible to design each circuit for maximum efficiency. I have also accomplished this by a simple and inexpensive construction, and I have simplified and strengthened the radiator which is the weakest link in the cooling system, by eliminating the necessity for an overhung top tank which is so universally used, and which is made to extend several inches back of the radiator core.

Furthermore, in my process I secure naturally a more rapid warming up of the cooling liquid in the jackets because this liquid as it is heated and as it comes out of the jackets follows the path of least resistance. and it circulates in the jacket circuit which, as already explained, has a very low heat dissipating capacity. As the cooling liquid is heated and as its tendency to rise is increased, it forces its way into the radiator circuit and brings this into action. However, if desired, I also use hand-operated or automatic means for retarding the flow of the cooling liquid through the radiator cirllfi cuit until and after the enginehas reached its operating temperature, without in any way interiering with the rate 01 flow -in-the jackets. Further, it will be easily seen that in my process the rate oi cooling down of the engine jackets after the engine is shut down is diminished, and as recent research has conclusively shown quick warming up and slow cooling down-greatly assist proper lubrication, reduce crankcase oil dilution and add materially to the useful life of the engins.

In all. of the figures A represents an inter,- nal combustion engine having a jacketed portion B through whicha liquid flows for cooling the cylinders of the engine A, and G rep -resentsa radiator or other cooling device in which the circulating liquid is cooled. All of these parts may be of any usual or suitable construction and of themselves constitute no part of'this invention.

all of the constructions shown, the liqi-ii-d discharge outletof the engine jackets is connected to the liquid receiving inlet of the jackets by means of apassage of comparatively large cross sectional area which is intended to other a very low resistance to the flow of liquid fromthe discharge-of the engine jackets to the inlet thereof, and this engine jacket circuit is not provided with any cooling-means or heat dissipating means, so that this circuit has a very low heat radiating capacity. The cooling circuit on the other hand, which includes the radiator C is adapted to .-tal :e a small portion of the water flowing through the jacket circuit, preferably from the upper portion of the jacket circuit, and after this portion of the water has been passedthrough the radiator or other cooling device, it is discharged into theengine jacket circuit in such a manner as to secure a thorough mixing of the cooled water with the warm water flowing in the engine jacket circuit.

In the particular construction shown in Fig. 1, 10 represents a return flow pipe or passage for the water which has been heated by passing around the engine jackets B. This tube or passage has a portion 11 which connects with the discharge opening for the hot water from the engine jacket, and'then extends downwardly, forming an upright portion or mixing chamber 12 oi the iengine jacket circuit. The lower end of the upright portion or mixing chamber 12 terminates in a rearwardly entendingpontion 13 which is connected with the water intake openingxof the engine jackets B. All portions of the conduit 10 are of large cross sectional area so that this conduit will otter very little-resistance'to the free convectional circulation of the cooling liquid from the liquid discharge opening of the engine manifold to the inlet open-ingtheueof. The engine jacket circuit consequently includes the engine jackets and the conduit 10 and contains no cooling device but -is arrangedin the form of a circuit of low frictional and head resist ances in which the liquid circulates rapidly when the engine is in operation.

The cooling of the liquid is accomplished by meansot the radiator or other cooling device (1, whicl-i is connected with the engine jacket circuit hymen-us of an inlet pipe or conduit 15 which carries liquid from the jacket circuit to the top of the radiator or cooling device 0, and a return pipe or passage 16 connecting the bottom of the radiator G with the mixing chamber 12 of the jacket circuit. Since it is essential to prevent circulation of cooling liquid through the radiator until the engine has'practically become warmed up to its normal running or operating temperature, means are provided in'several of the constructions shown for accomplishing this result. In the construction shown in Fig. 1, the inlet passage 15 leading to the cooling device C is provided with a substantially U-sh-aped bend 17 which accomplishes this result. Since the top of the radiator or cooling device is usually arranged at a higher level than the top of the engine jacket, a straight pipe connecting the top of the radiatornor cooling device with the engine jacket will permit the hot water to rise without delay into the radiator and to begin a circulation therethrough. However, loy using a :U-shaped bend or its equivalent, the warm currents of water which naturally rise, are constrained to flow downwardly in one portion of the U-shaped bend. and thus the circulation through the radiator is retarded until after the cooling liquid-in-the engine jackets has attained approximately its normal operating temperature, and until after the entire U-shaped bend has been heated, whereupon the difference intemperature between the liquid in the engine jacket circuit and the liquid in the radiator will cause and maintain a steady circulation.

It is desirable to provide means for in su-ring athorough n1ixing of the cool water discharged from the radiator or cooling device G into the jacket circuit so that all portions of the circulating liquid entering into the inlet opening of the jacket will be of a substa-l'itially uniform tem ierature. For this purpose the return pipe 16 from the rad-ia-tor circuit in the construction shown in Fig. l is extended upwardly into the mixing chamber 12 of the engine jacket circuit so that cold water will be discharged near the discharge portion 11 of the engine jacket and will thus be mixed with the liquid in the conduitlO while passing through the mixing chamber 12 and the portion 13 on"? the conduit 10. Preferably, the portion of the return wipe 1.6 which extends into the conduit 10 is also provided with a series of Hill perforations 19 which further insure proper mixing of the incoming cooled liquid with the liquid in the engine jacket circuit.

It will be noted that both of the circuits shown in Fig. I operate on the thermosiphon principle so that no pump or other positive circulating device is required and also this construction includes no valves and it has a natural or intrinsic temperature regulating action.

In the construction shown in Fig. 2, the conduit 20 of the engine jacket circuit is very similar to that shown in Fig. 1. In this construction the radiator inlet pipe connecting the jacket circuit with the top of the radiator or cooling device includes a substantially straight or horizontal portion 25 ter-' minating near the jacket circuit in a portion 26 which extends downwardly into the conduit 20 of the engine jacket circuit, considerably below the upper portion of the conduit. This downwardly extending portion 26 of the radiator inlet passage 25 will retard the rise of warm water and its en trance into the radiator circuit until some time after the engine has been started.

28 indicates the return tube or pipe from the lower portion of the radiator to the mixing chamber 22 to the engine jacket circuit passage 20. this tube terminating in the lower portion of the mixing chamber. In order to insure proper mixing of the liquid passing into the jacket circuit through the return pipe conduit 28 with the warmer liquid in the jacket circuit. a baiiie wall or plate 29 is preferably provided in the mixing chamber which extends upwardly from the bottom of the chamber. so that the cool liquid from the radiator circuit will flow over the wall of the baflie 29 and thus thoroughly mix with the warm liquid in the engine jacket circuit. 7

In the construction shown in Fig. 3, 30 represents the passage or conduit connect ing the discharge opening of the engine jacket and the inlet opening thereof, this passage corresponding substantially to those described in connection with Figs. 2 and 3. In this construction a radiator inlet tube passage 31 connects the upper portion or tank of the radiator C with the upper portion of the passage or conduit 30 of the engine jacket circuit. and a return tube 32 connects the lower portion of the radiator C with the mixing chamber of the conduit or passage 30. In this construction the flow of liquid through the radiator circuit may be controlled by hand, and for this purpose a valve 33 is arranged in the upper tank of the radiator C adjacent to the discharge end of the inlet tube or passage 31, the valve being pivoted on a bracket 34 and having an arm 35 which is connected with a rod 36 which may extend rearwardly to the dash or instrument board of a vehicle or into any other position in which it will be readily accessible by the operator of the engine. The valve, as shown, is in a position in which the flow of liquid through the radiator is retarded but not entirely stopped, since this is all that is required, and it is much easier and less expensive to provide a valve which will not entirely interrupt the flow of liquid through the radiator but will only retard the flow. When the rod 36 is drawn rearwardly from the position shown in Fig. 3, in other words to the right in this figure, the valve 33 will be swung on its pivot on the bracket 34 into a position in which it will not interfere in any way with the circulation of water through the radiator. 37 represents a battle or deflector arranged in the mixing chamber of the conduit or passage 30 just below the portion thereof at which the cool water from the radiator C is discharged into the jacket circuit by the return tube 32, and this bathe serves to cause the cool water coming into the jacket circuit to be thoroughly mixed therein.

In Fig. 4 a passage 40 forms a part of the engine jacket circuit, and the radiator is connected to the engine jacket circuit by means of an inlet tube 41 corresponding substantially to the inlet tube 31 shown in Fig. 3 and by a return tube 42 which is substantially identical to the return tube 32 in Fig. 3. In this construction, however, the valve for controlling the flow of liquid through the radiator circuit is located in the return tube 42 and is in the form of a butterfly valve, including a disk or plate 43 suitably mounted on a stem 44 journalled in the return tube 42 and adapted to be operated by means of a handle 45. Means can, of course, be provided for operating this valve from the dash or other convenient place, such means not being shown in this drawing, or the handle 45 can be set at the proper position, according to the season or climate. The plate or valve 43 is preferably some what smaller than the internal diameter of the return tube 42 so that even when the valve is set into a position to resist the flow of liquid in the return passage 42. the passage will not be entirely closed. 47, Fig. 4 represents a battle plate or deflector which is provided for insuring a thorough mixing of the cool water with the hot water. and which corresponds to the battle 37 described in connection with Fig. 3.

It will be obvious, of course, that if desired, the valves shown in Figs. 3 and 4 could be automatically operated by thermostatic or temperature responsive means whichwould retard the circulation in the radiator circuit until after the liquid in the mixing chamber has reached a predetermined value, and then either permit entirely free circulation or interfere with it to an extent necessary to counteract the effect of extremely cold weather. Such automatic or temperature responsive means, however, 'do not in any way interfere with the circulation in the jacket circuit and merely supplement the natural or intrinsic temperature, selfreguiating action of the system.

In the construction shown in Fig. 5, 50 represents the pipe or conduit connecting the discharge opening of theengine jacket with the inlet opening thereof, and the inlet and return tubes 51 and 52 respectively connecting the engine jacket circuit with the radiator G are substantially the same as shown in previous figures. The pipe or conduit 50 of the engine jacket circuit, however, is provided in this case with a special portion 54 forming a housing for a pump of any suitable kind for forcibly propelling the cooling liquid in the jacket circuit, the pump being driven in any usual or suitable manner (not shown) from the "engine. By using a pump, the flow of liquid through the engine jacket circuit can be speeded up to such an extent as to cool properly high power engines with comparatively small pumps and with a comparatively small power consumption. As explained before, in case of high duty engines, the difference in temperature of the various parts of the jackets becomes prohibitive, but in my system a stream of cooling liquid at a high rate of flow as it sweeps through the jackets, it nearly equalizes their temperature for the following two reasons. First, because the heat absorbing capacity of the cooling liquid increases with an increase in its rate of flow, and secondly because the temperature of the cooling liquid when it reaches the hottest parts of the jackets is only a few degrees higher than when it entered the jackets. Thus, instead of a slow sluggish cool stream entering the warm, lower parts of the jacket, and after it is heated, sweeping by the hottest parts of the jacket, I have a very rapidly moving stream of cooling liquid, with a high heat absorbing capacity sweep through the jackets and travel through the jackets with only a few degrees rise in its temperature. F urther, the presence of the pump in the jacket circuit can be made to increase the flow through the radiator circuit sulliciently to secure maximum cooling capacity for the radiator, without unduly increasing the pumping losses.

In Fig. 5, the portion 56 of the conduit 51 is shown as extending into the mixing chamber or passage 50 in order to retard the circulation in the radiator circuit until after the cooling liquid has attained approximately its normal operating temperature. Also a baffle 57 is shown to assist in the thorough mixing of the cool liquid coming from the radiator with the warm liquid coming from the engine jackets.

It is obvious that any of the devices shown in the previous figures can be incorporated into Fig. :7 without interfering with the action of the pump. Further, in high power engines, particularly those used for airplanes, when a pump is used, oil or other suitable cooling liquid can be substituted in place of water in order to increase the new ura'l ten'iperatu're regulating tendency of finy system. That my system is admirably well adapted to take advantage of the. great change in viscosity of such liquids with temperature, will be easily seen. In starting when the en ine and radiator aife cold,fthe viscos'i y of die cooling liquid w'i'll interfere with the circulation through the numerous and small radiator passages to a si'i'flici'ent de'gre'e to insure 'a very rapidxfvarmin'g up without unduly interfering with the circulation in the jacket circuit. As the engine warms up and the warm liquid begin'sto rise and to find its way intothe radiator circuit, circulation will begin and the necessary cooling will be supplied to the jacket circuit. After the engine has warmed up, if the airplane happens to be flying through a zone of high temperature, asthe temperature of the radiator is increased, the vis cosity of the liquid will be decrease-d, and consequently its rate of flow and its heat absorbing capacity will be increased. However, if the airplane encounters a cold region of, the 'atmosphere, as the radiator is cooled the viscosity of the cooling liquid will increase, and consequently its rate of flow and its capacity to absorb heat will decrease and thus there will be an automatic, natural temperature regulating action.

I claim as my invention:

1. The hereindescribed process of cooling an internal combustion engine having jackets for a cooling liquid, which consists of passing a current of cooling liquid rapidly past said jackets said current flowing in a circuit of low heat radiating capacity, simultaneously conducting portions of said liquid from said circuit through a cooling circuit and returnin comparatively small quantities of the cooled liquid from said cooling circuit to said first mentioned circuit.

,2. The hereindescribed process of cooling internal combustion engines having jackets around the portionsto be cooled, which consists of passing a current of cooling liquid rapidly through said jackets, said current flowing ina circuit of low resistance to flow and low heat radiating capacity, simultaneously conducting portions of said liquid from said circuit through a cooling circuit in which said portions of the liquid circulate less rapidly, and returning the cooled liquid from said cooling circuit to said first mentioned circuit.

3. The hereindescribed process of cooling internal combustion engines having jackets around the portions to be cooled, which consists of passing a comparatively large current of cooling liquid rapidly through said jackets, said currentflowing in a circuit of low heat radiating capacity, simultaneously conducting comparatively small portions of said liquid from said circuit through a cooling circuit and mixing the cooled liquid from said cooling circuit with the liquid in said first mentioned circuit before the mixed liquids pass to said cylinders.

4. The hereindescribed process of cooling the jacketed portions of an internal combustion engine, which consists of passing a current of cooling liquid rapidly through the jackets, said current flowing in a circuit of low heat radiating capacity, simultaneously conducting portions of said liquid from said circuit through a cooling circuit, returning the cooled liquid from said cooling circuit to said first mentioned circuit and retarding the flow of liquid in said cooling circuit when the engine is starting until the liquid in said first mentioned circuit has raised to nearly its normal operating temperature.

5. The herein described process of cooling the jacketed parts of an internal combustion engine, which consists of passing a current of cooling liquid rapidly through the jacket in a circuit of low resistance to the flow of liquid and of low heat radiating capacity, simultaneously cooling a portion only of said liquid and returning the cooled liquid in relatively small quantities to said circuit whereby because of the higher rate of circulation and the higher temperature of the liquid in the jacket circuit than in the cooling circuit, the prevailing temperature of the mixture is the engine temperature 6. The herein described process of cooling the jacketed parts of an internal combustion engine, which consists of passing a current of cooling liquid rapidly past the jackets in a circuit of low resistance to the flow of liquid and of low heat radiating capacity, simultaneously passing a relatively small portion of said liquid through a cooling circuit of relatively high resistance to the flow of liquid, and returning the cooled liquid to said first mentioned circuit.

7. The herein described process of cooling the jacketed parts of an internal combustion engine which consists of passing a current of cooling liquid rapidly past the jackets in a circuit of low resistance to the flow of liquid and passing a portion only of liquid at a lower rate of circulation through a circuit containing a cooling medium and offering a higher resistance to the flow of liquid than said first mentioned circuit so that comparatively small quantities of cool liquid are mixed with larger quantities of hot liquid.

8. In a cooling system for internal combustion engines having cylinders provided with jackets, said jackets having inlet and outlet openings for the continuous circulation of a cooling liquid at a high rate, the combination or a passage of low resistance to flow connecting said inlet and outlet openings, and a cooling circuit which receives a portion only of the water circulating in said passage and which includes a cooling device for said liquid and connections for conducting warm liquid to the top of said cooling device and withdrawing cool liquid from the bottom of said cooling device, said connections terminating in said passage whereby because of the higher rate of circulation and the higher temperature of the liquid in the jacket circuit than in the cooling circuit, the prevailing temperature of the mixture is the engine temperature.

9. In a system for cooling an internal combustion engine, the combination with the jackets of an engine, of a low resistance passage connecting the discharge and the inlet openings of said jacket, a cooling device, passages connecting at all times said cooling device with said low resistance passage, and means for retarding the flow of liquid to said cooling device until the temperature of the liquid in said low resistance passage has been raised.

10. The herein described process of cooling the jacketed parts of an internal combustion engine, which consists in providing a rapidly flowing current of cooling liquid, cooling a portion only of said liquid, and adding cooled liquid to said circuit in such small quantities as to maintain a small difference in temperatures between the liquid entering and leaving the engine jackets.

11. In a system for cooling an internal combustion engine having jackets through which liquid can circulate, the combination of a low resistance mixing chamber connected with said jackets and through which the liquid passing through the jackets may circulate rapidly, a cooling device, means for conducting a portion of the liquid circulating in sald chamber to said cooling device, means for transmitting the cooled liquid from said cooling device to said mixing chamber for mixing the cooled liquid with a warm liquid circulating in said chamber, and means for retarding the flow of liquid through said cooling device without positively interrupting the fiow thereof until the liquid in said chamber has been warmed.

12. The herein described process of cooling the jacketed parts of an internal combustion engine, which consists in providing a rapidly flowing current of cooling liquid, cooling a portion of said liquid by passing it through a cooler at a rate of flow inferior to the rate of flow through said jacketed parts, mixing the rapidly flowing current with the less rapidly flowing current so as to maintain a small difierence in temperathrough a cooler, and providing means for 10 tures between the liquid entering and leaving mixing said two currents of cooling liquid the engine jackets. and returning said mixture to the engine 13. The herein described process of cooljacketed parts of the engine so as to maining the jacketed parts of an internal comtain a small diiference in the temperatures bustion engine which consists in providing between the liquid entering and leaving the 15 a rapidly flowing current of cooling liquid jacketed parts of the engine. through said jacketed parts, providing a less rapidly flowing current of cooling liquid NICHOLAS S. DIAMANT. 

